1. Field of the Invention
The present invention relates to an electrically powered motor.
2. Description of the Related Art
In the past, a spindle motor that rotates a disk has been mounted on a hard disk drive apparatus. In a so-called fixed shaft type spindle motor, a double-sided support structure where a shaft is supported at both end portions is adopted. Such a spindle motor has a structure which has very high structural rigidity and is suitable for the demand for higher capacity in a hard disk drive apparatus. A fixed shaft type spindle motor disclosed in Japanese Patent Application Publication No. 2009-136143 includes a shaft, a rotor component, a bearing component, and a bottom plate.
The bottom plate has a central opening portion of a substantially cylindrical shape and the bearing component is accommodated therein. The bearing component is formed substantially in a cup shape and includes an opening portion at the center. The shaft is fixed to the opening portion of the bearing component. A radial bearing portion is defined between axially extending bearing surfaces of the shaft and the rotor component that face each other. Further, the shaft has a threaded hole for mounting it on the spindle motor or a housing lid of a hard disk drive at an upper end portion thereof. Then, in a hard disk drive apparatus on which the spindle motor as disclosed in Japanese Patent Application Publication No. 2009-136143 is mounted, the shaft is fixed to the housing lid by a screw. In such a hard disk drive apparatus, a portion in the vicinity of a threaded hole of the housing lid is recessed downward so that a flange portion of the screw does not protrude upward.
Incidentally, in a hard disk drive apparatus, a reduction in thickness is required in addition to higher capacity. However, in the hard disk drive apparatus on which the spindle motor disclosed in Japanese Patent Application Publication No. 2009-136143 is mounted, if attempting to secure the axial length of the radial bearing portion of the spindle motor, a reduction in thickness cannot be achieved.